So this is a topic you don't often hear much discussion about. Forum games. The Escapist has a section dedicated to these kind of games, as do quite a lot of other forums. Many of these take the forms of RPGs. Personally though, I find the best ones tend to be when there is an entire site dedicated to the one game. It seems to allow for a level of complexity and independent community that doesn't really have a chance to develop when you're only working in one or two topics (although I have seen exceptions). My fondest memories of forum gaming come from games like the World of Arl and The Nether (I don't recommend anyone checking out the latter, my vague memories of how things came to an end there involved a lot of porn-related spambots or something, by which point the Admins and mods had all quit and so there was no one to delete them).

Currently I'm waiting for the next round of Zanzibar to start up. Zanzibar, for those interested, is a sort of a world-building/strategy game where you invent a civilisation and, if the GMs deem it good enough, get entered into the era to interact, trade, and (naturally) fight against the other cultures that were picked for the era. You play as your nation's leader and are solely in charge of every aspect of your nation (although you can also take on board seconds from the players that didn't get picked, who can run part of your nation for you). Like all things related to forum gaming it can be incredibly slow-paced, taking roughly a year to run through an era. It's fantastic fun though, as the fact that results are computed by living, breathing GMs and that results are presented as a written story allow for your actions to literally be anything you could feasibly expect a fantasy nation with access to magic and the favour of their gods to achieve.

So, who else here plays games in a similar vein? They don't have to be the same kind of genre as Zanzibar, just that they're based on forums. I love the amount of freedom and imagination that can come into play in these games, many of them share many awesome qualities with tabletop RPGs and the like.